The invention relates to a filling machine for open, sealable sacks, having a fill pipe for filling the attached sacks with contents that tend to develop dust, and at least one blow rail which is acted upon by compressed air and arranged preferably above the sack mouth rim for allowing dirt particles to be removed.
Filling machines of a type involved here fill various contents. Powdery contents in particular tend to develop dust during the filling operation. As sacks are made preferably of sealable material, it is absolutely necessary to keep at least the inner surfaces in the area of the welding seam free of dirt particles as otherwise leaks are encountered through which the material particles may escape.
Constructive measures on the fill pipe are known to protect the inner surfaces of the sack mouth rim from contamination during the filling operation. According to a standard configuration, each fill pipe is equipped with at least one suction pipe which can be connected to a dedusting unit. In this way, the surroundings of the filling machine should be kept as free of dust as possible.
When the filled sack is removed from the fill pipe, it is also known, while the clamping jaws are closed, to expose the sack mouth rim situated above the clamping jaws to air from a blow rail so as to expel adhering material particles.
In particular, when sacks of plastic film are involved, it is unavoidable that the so-called overhang comprised of both sack walls oftentimes does not open so that blow air is unable to reach the inner surfaces. In this case, cleaning is inadequate.
It is further known to move a blow element, preferably in the form of a blow finger, in longitudinal direction of the sack rim so that the air jet is guided between both layers of the sack mouth rim. This arrangement has in particular the drawback that the sack overhang must already be opened beforehand or spread apart in order to allow the blow element to dip into it. Moreover, this construction has also the drawback that at least one of both side folds is not sufficiently cleaned. Therefore, this solution has been shown inadequate in practice.